Ferroelectric Characteristics of Hf0.5Zr0.5O2-Based Mfis and Mfmis Capacitors for Steep-Slope Ferroelectric Field Effect Transistor Applications

Abstract

Research of hafnium oxide-based ferroelectric materials has attracted much attention in the community with superior advantages of their compatibility with silicon. Also, negative capacitance (NC) effect from ferroelectric films attracts a great deal of attention because it could be one of the solutions for the high power-consumption issue of field effect transistors (FET). However, since the non-linear Q-V response of semiconductor in the FET structure in conjunction with the domain formation in the ferroelectric layer resulted in complicated device behaviors, it is necessary to understand the physics of the ferroelectric characteristics related to the interactions among the layers such as the depolarization field and charge trapping/injection for sub-60mV/dec subthreshold swing (SS) operation. In this study, the electrical properties of a Metal-Ferroelectric-Insulator-Semiconductor (MFIS) capacitor with a 7-10nm Hf0.5Zr0.5O2 (HZO) ferroelectric layer and an ultrathin interfacial oxide layer (SiO2) were examined in order to understand the underlying physics of the ferroelectric characteristics (Figure 1 (a)). These properties were compared with those of a Metal-Ferroelectric-Metal-Insulator-Semiconductor (MFMIS) capacitor to analyze the interactions among each layer in the two different structures by pulse measurement. In addition, the ferroelectric characteristics of HZO on semiconductor related to the charge injection through the interfacial oxide layer with different thicknesses and the non-linear Q-V response of semiconductor have been investigated (Figure 1 (b)). Lastly, the effects of different PMA temperatures and HZO thicknesses were also examined and the experimental data were verified by the charge injection-controlled simulation model which was used to simulate the transfer characteristics based on different experimental conditions. (Figure 2). Figure 1